The present invention relates to a check valve and, more particularly, to one which, when placed on a pump suction pipe, allows the pump to draw fluid intermittently from a fluid source located below the level of the pump, without the necessity of priming the pump each time the pump is started.
In many instances, it is desired to remove fluid over an extended period of time from a below-ground fluid source which is continually replenished, such as a well or sump. A convenient and economical means for removing such fluid is to position a pump on ground level just outside of the fluid source and lower a suction pipe, attached to the pump suction port, into the fluid source. Each time the fluid in the fluid source rises to a predetermined level, the pump is switched on to draw the fluid up and out of the fluid source. When the fluid level has been drawn down below the level of the suction pipe inlet, the pump is switched off.
As an example of the foregoing, when a portion of the soil becomes contaminated, a technique known as soil vacuum extraction may be used to clean up the affected area. In accordance with this technique, a number of wells are dug at the affected site. The purpose for these wells is to collect contaminated ground water and rainwater as it percolates through the contaminated soil. The wells fill with contaminated water and are pumped dry, or down to any desired level, on a continuous basis. The contaminated water is collected and treated to remove the contaminants therefrom. This cycle continues until all, or substantially all, of the contaminants are removed from the affected site.
As another example, bacteria are sometimes placed into the soil at contaminated soil sites to ingest the contaminant. To keep the bacteria viable, they must be supplied with replenishment fluids on a continuous basis. Because the replenishment fluids can become contaminated, wells are dug at the affected site to collect the fluids. As with the previous example, the wells are continually pumped as they fill with the replenishment fluids so that the fluids can be collected and treated.
As a further example, containments are often used to prevent contaminated fluids from escaping a contained area, such as a landfill. In the case of a landfill, a containment may take the form of a berm or dam which encircles the landfill. One or more sumps may be placed between the landfill and the containment to collect any runoff rainwater or other fluids. As the sumps fill with contaminated fluid, they are pumped dry or nearly so on a continuous basis so that the collected fluid can be removed and treated.
With known pumping arrangements, once the fluid in the fluid source has been pumped down to a level below that of the suction pipe inlet, all of the remaining fluid in the pump suction pipe will either be drawn into the pump or will fall back into the fluid source due to a vacuum break in the suction pipe. When this situation occurs, the pump must be primed before pumping can be resumed as required (i.e. when the fluid level has risen above the suction pipe inlet). Pump priming involves filling the pump and suction pipe with fluid prior to starting the pump.
The continual loss of pump prime and the resultant necessity to re-prime the pump prior to each pump start greatly encumbers the removal of fluids from continuously replenished fluid sources. In the first place, pump priming is generally a manual operation. Although self-priming pumps exist, they typically do not possess sufficient priming capability to be of use in the removal of fluids from below-ground fluid sources. Thus, the removal operation cannot be automated. Instead, vigilant surveillance and frequent manipulation of the pumping operation is needed. When the level of fluid in the fluid source has been pumped down below the level of the suction pipe inlet (such that fluid is no longer being drawn into the pump), the pump must be shut off soon thereafter to avoid damage thereto. Surveillance is further needed to ensure that the pump is primed and switched on again at the appropriate time. Fluid removal operations from wells, sumps, and the like frequently take place at remote sites. Thus, the manual presence and involvement necessitated by the continuous loss of pump prime is quite burdensome, as well as inefficient. It would be highly desirable to be able to automate such fluid removal processes
Accordingly, it is seen that a need exists in the art for a means of removing fluids from a continuously replenished, below-ground fluid source which will maintain the prime of a pump positioned outside the fluid source so that the pump can be stopped and started without having to be primed each time. Such means would allow such fluid removal operations to be automated.